The present disclosure relates generally to the field of display systems. More specifically, the present disclosure relates to a method for displaying radar-estimated terrain on a flight display in an aircraft.
Terrain awareness warning systems provide aircrews with information regarding the terrain. Standard TSO-C151b is utilized by the Federal Aviation Administration (“FAA”) to specify four functions for a terrain awareness warning system. These functions are terrain display, premature descent alerting, ground proximity alerting and forward-looking terrain alerting. The terrain information is transmitted to a display, which provides alerts for the aircrew.
The terrain display allows the pilot to estimate the distance and bearing to terrain cells of interest. The display can be oriented with the aircraft positioned at the bottom of the display and the track of the aircraft in the upward direction; however, other orientations are allowed by the regulations.
The display is formatted in such a way as to ensure that the pilot can differentiate between terrain that is above the aircraft and terrain that is below the aircraft. The display also provides a means to distinguish between terrain cells that represent a potential hazard to the aircraft and non-hazardous terrain cells.
The color scheme for the terrain display can be determined through extensive prototyping and human factors studies. The following colors are commonly used in terrain displays. Blue or cyan for the sky. Red for terrain above the aircraft's altitude. Yellow or amber for terrain just below the aircraft's altitude. A neutral color for terrain that is well below the aircraft's altitude (i.e., non-hazardous terrain). The neutral color may be green, brown, tan, some other pastel color, or even a photo-realistic rendering.
Terrain awareness warning system can utilize a database to generate the display image. Terrain awareness warning system displays that use databases are subject to three basic error conditions, including position errors from the navigation system (e.g. the Global Positioning System (“GPS”), altitude or heading errors from the inertial sensors (e.g. the Altitude Heading Reference System (“AHRS”)), and terrain elevation errors from the terrain database. These error sources can cause significant problems for aircrews.
There is a need for a method of displaying terrain utilizing an enhanced vision system and a radar system to provide and/or validate a terrain display. Therefore, there is a need for an improved method of creating a terrain image such that the pilot of the aircraft can make better-informed decisions.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.